Whitebark pine at risk of extinction
Peter Achuff, scientist emeritus with the Ecological Integrity Branch of Parks Canada, said Thursday (May 13) Alberta and B.C. are home to an estimated 200 million whitebark pine and the current situation is looking bleak.
“For many species to get into trouble the threats can be mitigated. But with this one, we don’t know how to control any of these things really.
“That’s why we are concerned about climate change over the next 50 years. You put the interacting impacts blister rust, pine beetle, fire exclusion, climate change and it doesn’t look good,” Achuff said.
While the whitebark pine and its close relative the limber pine were listed as endangered species in Alberta in 2009, according to Cyndi Smith, ecosystem scientist for Waterton Lakes National Parks, the COSEWIC recommendation adds support and credence, and hopefully if the recommendation is accepted by the federal government, more money for restoration and protection efforts currently underway or planned.
“At this point until it is legally listed (in Canada) it doesn’t change a lot, but it does raise awareness for everybody and our policy has been, when it has been assessed, we start to treat it almost as if it was listed,” she said, adding efforts to protect both the whitebark and limber pine have been ongoing for a decade now.
“So really it is these four things often working in synergy because a tree that is stressed by blister rust is more susceptible to pine beetles and same with drought stress. If we are getting warmer winters and hotter summers, with drier conditions the tree gets stressed and it may be more susceptible to beetles as well,” she said.
Even though all four factors have conspired to create a deadly cocktail, Smith pointed out the pine blister rust, introduced to North America from Asia via European seedling stock, has been the primary culprit to date.
Blister rust was introduced about a century ago, but the yellow fungus was not discovered in Alberta until the 1950s.
The fungus generally weakens a tree by attacking the stem and the branches, which can make it susceptible to other factors, such as pine beetle or drought.
In some cases, a tree infected by blister rust will survive, but is rendered infertile.
“Often what you get is a top killed tree. The top of the tree dies and that is the area where cones are produced, so even though the tree might live, it will never produce cones. It is reproductively dead,” she said.
Whitebark pine is a slow growing, small-to-medium sized tree that grows in sun-filled clearings from California through to Jasper National Park and the Willmore wilderness.
The pine can be readily outcompeted by faster growing spruce and fir trees if wild fires are not allowed to burn.
As part of her work, Smith led research projects in the mountain parks in 2003-04 and again in 2009 to assess the health of the population.
Researchers found Waterton, and southern Alberta, are in the worst situation in the province with blister rust infection rates of 73 per cent.
In the central Rockies, including the Bow Valley region, Smith said 2003-04 demonstrated that 16 per cent of whitebark pines in the study plots were infected, while in 2009, that number had increased 20 per cent. Of the trees that were still alive, 36 per cent had been infected with blister rust.
In Jasper, the number was much higher. An estimated 60 per cent of whitebark pine trees in the study plots were infected with blister rust.
Even though Smith said the rates in the Banff region are still relatively low, it was the site of one of the first prescribed fires in Banff National Park, ignited near Helen Lake in 1998, used to create clearings for whitebark pine, a species Achuff described as a keystone species as it sits in the middle of a number of different interactions.
Both grizzly and black bears rely on the seeds, or nuts, as a food source, as does the red squirrel and the Clark’s nutcracker, which has a unique connection to the whitebark pine.
The Clark’s nutcracker, a pigeon-sized bird, with a long, curved beak, gray body and black wings and tail tipped in white, co-evolved with the whitebark pine and is solely responsible for dispersing the nuts.
These raucous members of the crow family cache the pine seeds by planting them in subalpine clearings; seeds that aren’t eaten can germinate and grow.
Possibly, if the whitebark pine declines further, it could put the nutcracker at risk, as well, Smith said.
Nutcrackers can and do eat other foods, but the nutritious seed of the whitebark pine is especially important for the birds, given the seeds – like pine nuts thrown into a salad – are high in fat and protein.
The gnarled whitebark pine with its long tightly packed bundles of five needles also provides an environmental service by holding snow in large drifts at treeline, allowing the snow to melt gradually.
“There is some concern from a watershed standpoint, as these species die, there could be changes to they hydrology of the watershed,” Smith said.
But as restoration programs are well underway, in conjunction with the recommendation to list the tree as endangered nationally, both Smith and Achuff believe there is hope.
“Again, it is this keystone species thing and it is linked in many important ways to a lot of other species and if it disappears out of the system, it is going to affect a number of species negatively.
“It is a long shot at this point, just because of the number of threats and the interactions but there are some possibilities and we are working on those and we may find some breakthroughs,” Achuff said.
Some whitebark pines appear to have a resistance to blister rust and researchers are actively collecting seeds, germinating them and then planting seedlings back into high mountain clearings in the hopes that those seeds will have the same resistance.
“It’s a slow growing tree so it is going to be a while before we see much progress on the ground. It really is a work of faith in what we are doing. We work with colleagues in the U.S. who have been doing this longer and learning from them,” she said.
The whitebark pine recovery team is also planning a comprehensive whitebark pine survey, while Achuff said a University of British Columbia graduate student is working on a project to see if the tree can be migrated artificially by planting seeds in northern B.C. and the Yukon, north of the tree’s current range, but where the climate will be more suitable as planet warms.
“Move it to where the habitat is moving to and see what is involved biologically and logistically. That is a possibility. We may not have it in southern Canada just because the climate isn’t here, we’ll probably have something else, its habitat may not be here but further north and we may be able to keep it in the system by moving it to where the habitat is favourable.”